Field of the Invention
The present disclosure relates to a touch display device. More particularly, the disclosure relates to a touch display device including a touch driver IC integrated with a display driver IC.
Discussion of the Related Art
With an information-based society, the display field has advanced rapidly. To meet this rapid growth, flat panel display (FPD) devices having thin profile, light weight and low power consumption, such as a liquid crystal display (LCD) device, a plasma display panel (PDP), an organic light emitting diode (OLED) display device and a field emission display (FED) device, have been developed.
The FPD device is operated in response to a stimulation to an outer surface of a display panel, i.e., a touch to provide convenience to a user. In other words, the FPD provides a function of a touch panel together.
The touch panel is used as an output means that displays an image, and also is widely used as an input means that receives a user's instruction through touching a creation portion of the displayed image.
In other words, when a user touches a touch panel watching an imaged displayed on a display panel, the touch panel detects location information of the touched portion. The detected location information is compared with location information of the image, and thus a user's instruction is recognized.
The touch panel may be categorized into a resistive type, a capacitive type, a IR (infrared ray) type, and a SAW (surface acoustic wave) type. A capacitance-sensing type touch panel or pressure-sensing type touch panel is used as a representative touch panel.
This touch panel is manufactured by an add-on method to attach a touch panel on a display panel, or is manufactured by an on-cell method or in-cell method to form a touch panel on a substrate of a display panel and integrate a touch panel and a display panel.
A touch display device using the touch panel includes a display driver IC to display image, and a touch driver IC to sense touch.
FIG. 1 is a view illustrating an add-on type touch display device according to the related art.
Referring to FIG. 1, the add-on type touch display device includes a display panel 1 and an touch panel 11.
The display panel 1 includes a plurality of gate lines and a plurality of data lines crossing each other to define a plurality of pixel regions which are in a display region AA and each include a thin film transistor, a common electrode and a pixel electrode, a display driver IC (D-IC) 7 to input signals to the gate and data lines, first link lines 5 connecting the display region AA with the D-IC 7, a first flexible printed circuit board (FPC) 10 transferring image data and timing signals such as synchronization signals from an external system to the D-IC 7, and first connection lines 9 connecting the D-IC 7 with the first FPC 10.
The touch panel 11 includes a touch region TA including a plurality of electrode patterns to sense a touch, a touch driver IC (T-IC) 17 which generates touch signals and applies the touch signals to the electrode patterns, then receives touch sensing signals according to the applied touch signals, and senses a touch input location in the touch region TA, second link lines 15 connecting the electrode patterns with the T-IC 17, and a second flexible printed circuit board (FPC) 20 which the T-IC 17 is installed on and receives signals from the external system.
The display panel 1 and the touch panel 11 are attached to each other to manufacture the touch display device.
It is difficult to make the add-on type touch display device thin-profiled because the electrode patterns are formed in the touch panel 11. To solve this problem, proposed is an in-cell type in which electrode patterns such as driving electrodes and sensing electrodes are formed in a display panel.
FIG. 2 is a view illustrating an in-cell type touch display device according to the related art.
An in-cell type touch display device may be categorized as a self-capacitance type or a mutual capacitance type. The mutual-capacitance type is explained hereinafter.
Referring to FIG. 2, the in-cell type touch display device includes a touch display panel 31 and a D-IC 37 and T-IC 43.
The touch display panel 31 is a flat display panel, for example, an LCD panel, an OLED panel, or FED panel.
In case of the LCD panel, the touch display panel 31 includes a lower substrate, an upper substrate and a liquid crystal layer between the lower substrate and the upper substrate.
The lower substrate includes a plurality of gate lines and a plurality of data lines crossing each other to define a plurality of pixel regions in a display region AA, and a thin film transistor, a pixel electrode connected to the thin film transistor, and a common electrode in each pixel region.
Further, the lower substrate includes a touch region TA where a plurality of driving electrodes and a plurality of sensing electrodes are formed using common electrodes or touch lines. The driving electrode may cover pixel regions on a row line parallel with the gate line, and the sensing electrode may cover pixel regions on a column line parallel with the data line.
The touch display device includes a display driver IC (D-IC) 37 to input signals to the gate and data lines, third link lines 35 connecting the display region AA with the D-IC 37, a third flexible printed circuit board (FPC) 40 transferring image data and timing signals such as synchronization signals from an external system to the D-IC 37, and second connection lines 39 connecting the D-IC with the third FPC 40. The third link lines 35 and the second connection lines 39 are formed on the lower substrate, and the D-IC 37 is mounted on the lower substrate.
The touch driver IC (T-IC) 43 sensing a touch input location is installed on the third FPC 40.
The lower substrate is attached to an upper substrate, which may includes a color filter and a black matrix, with the liquid crystal layer therebetween.
In the in-cell type touch display device, driving electrode and the sensing electrode are formed near the gate line and the data line, and this influences a capacitor formed between the driving electrode and the sensing electrode. In detail, a voltage variation of the gate line near the data line influences the data line, and a variation of the data line causes a coupling with an adjacent driving electrode.
Further, a sensing electrode near the data line is influenced by a parasitic capacitor formed by a variation of the data line, and thus a RC (resistive-capacitive) delay increases. In other words, a touch precision is reduced due to a coupling interference, and a response speed is reduced by an influence of a parasitic capacitor.
In case of the in-cell type touch display device configured in a self-capacitance type, common electrodes do not form both driving electrodes and sensing electrodes. A group of common electrodes in a predetermined region define a touch electrode, and touch electrode lines are independently selected from the touch electrode.
Considering a number “n” of touch electrodes in a row direction and a number “m” of touch electrodes in a column direction, a number “n*m” of line channels is required.
Accordingly, the T-IC 43 needs a number “n*m” of actual channels. If a number of channels of the T-IC 43 is lacking, a plurality of T-ICs 43 is required, and in this case, the third FPC 40 having the T-IC 43 thereon increases in size and is complicated in wiring arrangement.
Instead of using the plurality of T-ICs 43, a multiplexer (MUX) may be embedded in the D-IC 37. However, this causes an increase of size of the D-IC 37 and increase in cost. Further, the third FPC 40 increases in size and is complicated in wiring arrangement.
Besides the above problems, since the touch display device of the related art uses both the D-IC and the T-IC, production cost increases, and noise between the D-IC and T-IC and their peripheral elements (e.g., wirings) occurs.